Resistance meter



D. J. ANGUS RESISTANCE METER Filed May 14. i921 2 Sheds-Sheetlelm/vanter, DONAL D IHN GUS,

AugQzs, 1924. 19506552 D. J. ANGUS v RES ISTANCE METER Filed May 14.1921 2 shank-sheet 2 DONALD I HNGUS,

attentat,

Patented Aug. 26, 1924.

UNITED STATES DONALD J'. ANGUS, 0F INDIANAPOLIS, INDIANA.

RESISTANCE METER.

Application led Hay 14, 1921. Serial No. 469,734.

To all whom t may concern.'

Be it known that I, DONALD J. Anous, a citizen of the United States,residing at Indianapolis, in the county of Marion and State of Indiana,have invented a new and useful Resistance Meter, of which the followingis a'specification.

It is the object of my invention to measure electrical resistancedirectly, by a device operable by alternating currents and substantiallyindependent of voltage and frequency and wave-form and giving a directreadin of the value of the resistance being measure In carrying out myinvention in its preferred form, I produce electromagnetically twoopposing pulls on an indicating or recording device, one of such pullsbeing dependent on and the other independent of a current passingthrough the resistance to be measured, and as either of such pullsredominates and produces a movement of the indicating or recordingdevice I cause such movement to weaken relatively the predominating pulland strengthen relatively the other pull until equilibrium.is obtained.If the instrument is properly calibrated, the position of the indicatingor recording device now gives directly the value o the resistance beingmeasured.

I obtain these opposing pulls, in the preferred form of my invention, bytwo opposing induction-meter elements, the secondary coil of one ofwhich is arranged to have the resistance to be measured connected incircuit with it; these two induction-meter elements conveniently act onthe same eddycurrent plate though this is not essential, and tend toturn oppositel the eddy-current plate or plates; and the eddy-currentplate or plates are so arranged, preferably by having the edge or edgescut away as shown, so that as either meter element predominates andproduces movement of such plate or plates the conductance of thepermissible path for eddy currents in the associated eddy-current plateis reduced, thus diminishing the pull of that induction-meter element,while at the same time the conductance of the permissible path for theeddy currents of the other induction-meter element is increased, topermit larger eddy currents, so that the pull from the lastnamed meterelement is increased, until equilibrium is produced. I prefer to providefor the increase of the conductance of the eddy-current path of oneinductionmeter element at the same time that that of the other isdecreased, though this is not essential, and it is sufficient if theconductance of the eddy-current path of only one of the meter elementsis made to vary. In the preferred form of my invention the two meterelements are combined so that they may have a common main excitingwinding, though this is not essential.

The accompanying drawings-illustrate my invention: Fig. 1 is afragmentary perspective view showing the elements of my resistance meterin a recording meter; Fig. 2 is a plan of the parts shown in Fig. 1;Fig. 3 is a diagrammatic vertical section through the parts shown inFig. 1, indicating one set of connections for the instruments; Figs. 4,5, and 6 are diagrammatic views, somewhat similar to Fig. 3, showingother arrangements of connections; and Fi 7 is a diagram of amodification in whic the secondary coils and the main exciting coil areon different members.

In the preferred form of my resistance meter, as shown in Figs. 1 to 6inclusive, a laminated core 10 has a main exciting winding 11 around itsintermediate portion, and two pairs of laterally projecting fingers, 12and 13, and 14 and 15, from its respective ends, the free ends of allthe fingers 12, 13, 14, and 15 conveniently being in the same plane. Aneddy-current plate 16 lies close to the ends of thet fingers 12, 13,14,and 15, and on the opposite side of such plate is a laminated member 17of magnetic material for completing the magnetic circuit. Theeddy-current plate 16 is suitably mounted to oscillate, as by beingfixed on a vertical shaft 18, which carries a suitable indicating orrecording device, such as a pen 19 which cooperates with a moving chart20 driven by the usual clock-work, and a. pointer 21 movable in front ofa suitable scale 22 for visual indication.

One of each pair of fingers 12 and 13, and 14 and 15, is provided with asecondary coil upon it, while the other is unwound; as shown, the finger12 is provided with a secondary coil 23, and the finger 15 with asecondary coil 24, the fingers 13 and 14 being unwound. One of thesesecondary coils, say 23, is permanently connected in series with aresistance 25, of fixed value; while the other, say 24, may be connectedin series with the resistance'26 the value of which is to be measured,conveniently being provided in its circuit with binding posts 27 formaking such connection to different resistances. The secondary-coilsl 23and 24 may have their circuits completed through thelr respectiveresistances 25 and 26 alone, as indicated in Figs. 1 and 3; or they maybe connected in series with such resistances across a suitablealternating-current exciting circuit v28, as is indicated in Fig. 4, theconnection either being direct as indicated for the coil 23 or throu h atransformer 29 as indicated for the coi 24; or one of the secondarycoils 23 and 24 may have its circuit completed throu h its associatedresistance alone, while t e other is connected vto the vexciting circuitin series with its associated resistance, as is indicated in Figs. 5 and6.- The main exciting Winding 11 is connected across a suitablealternating-cur- .'rent exciting circuit 28, which will ordinaril be thesame exciting circuit as that` for t eI secondaryl coils 23 and 24 whenthe latter are connected to an exciting circuit, as shown'in Figs. 4, 5,and 6.

The two pairs of fingers 12 and 13,v and 14 and. 15, are in effect twoinduction-meter elements, when considered in conjunction with thecorresponding parts of the core 10 and theedd'y-current plate and themember 17; and these two induction-meter elements are arranged to-actoppositely on the eddy-current plate 16, so that the action of thefingers 12 and 13 tends to turn such plate in a clockwise direction(Figs. 1 and 2) and that of the fingers 14 and 15 tends to turn it in acounter-clockwise direction. To make this clear it will be sufficient torefer tothe action ofthe fingers 12 and 13 in Fig. 3, the action of theother pair of fingers being similar. The excitation of the core 10 bythe main winding 11 causes a main alternating 'flux to pass through theeddy-cur rent plate 16 from the fingers 12 and 13 to the member 17, thusproducing in such eddycurrent plate eddy currents in approximatequadrature with such flux. Currents are induced in the secondary coil 23by this same main flux, and these induced currents and the flux whichthey produce are in approximate quadrature with the main iux and soinf-phase with the eddy currents in the plate .16 at the finger '13. Thepath of this secondary ux is mainly from the finger 12 through the mainbody of the core 10 to the nger 13, and thence through the eddy-currentplate 16 into the member 17 and back, thus in the .main not passingthrough that part of the core 10 which carries the main winding 11. Thissecondary flux, being in phase with the eddy currents produced by themain flux in the late v16 at the finger 13, reacts with such el dycurrents, and tends to turn the eddy-current plate 16 in clock-wisedirection (Figs. l and 2). This secondary flux also induces its own eddcurrents in the eddy-current plate 16, which latter eddy currents are inquadrature with the secondary fiux, and so 1n phase with the main fiux;and these eddy currents from the secondary flux react with the main fluxto produce also a tendency to turn the plate 16 in a clockwisedirection. Thus the two fluxes and the two sets of eddy currentscooperate to produce thsame tendency to turn the eddy-current pla e 16.

A similar action takes place at the other pair of fingers 14 and 15,save that there the tendency is to turn the eddy-current plate in theopposite direction.

The forces with which these turnin tendencies act vary with the currentsin t e secondary coils 23 and 24. Such current is constant in thesecondary coil 23, (assuming nothing else is changed), because theresistance 25 is a fixed resistance; but it varies in the secondary coil24 in inverse sense tothe value of the resistance 26. Thus the relationbetween the opposing turning forces on the eddy-current plate 16 variesas the resistance 26 is varied, causing one or the other of such forcesto predominate. The force which thus predominates produces an actualmovement of the eddy-current plate 16 in the corresponding direction,clockwise if the turning force fromthe lingers 12 and 13 predominatesand counter-clockwise if that from the fingers 14 and 15 predominates.

This movement would be continued indefinitely, in the absence ofsomething to sto it, 1f the eddy-current .plate 16 were a dis of uniformconductance throughout. However, it is not of uniform conductancethroughout. Thus variable conductance is obtained, as. shown, |by makingthe eddycurrent plate not a disk, but providing it with an edge 30 whichis eccentric with respect to the turning axis of the plate (the shaft18); so that as the plate is turned in one direction by the redominanceof the turning force produced) by one pair of fingers the distance ofthe edge of the plate from the axis at such fingers diminishes, and thusin effect the ledge of the plate moves inward relatively to the faces ofthe fingers which produce the predominating effect, and so cuts down theconductance of the possible path for the eddy currents in such plate atsuch fingers. By thus cutting down such conductance, the eddy currentsthemselves are valso cut down, and by the cutting down of such eddycurrents the turning force exerted on the plate is also cut down, sothat the force which predominates to produce the movement of theeddy-current plate decreases as the movement it produces continues.Thevreverse effect takes place at the other pair of fingers, themovement of the eddy-current plate causing an' increasein the radiusof'. such -plate at such fingers and thus increasing4 the conductance ofthe path for eddy currents, thereby increasing the eddy currentsthemselves, and thus increasing the opposing force which is produced atsuch fingers yb the reaction of such eddy currents wit the fluxes, andso causin an increase in Ithe turning force exerte on the plate 16 .atthe air of fin ers which initially produced t e smaller orce. As aresult of this decrease in the initially predominating force and thisincrease in the initially smaller force, the movement of theeddy-current plate eventually causes such two forces tobecome equalagain, at a new position of equilibrium of the plate 16. Other thingsbeingequal, and the resistance 25 being constant, there will be adefinite position of the plate 16, and therefore of the pen 19 andpointer 2l, for each value of the resistance 26. By proper calibrationof the instrument, it is t us possible to obtain a direct reading on thescale 22 and a direct indication on 'the chart 20 of the value of theresistance 26, an'd -a continuous record on such chart of the changes inthe value of such resistance if the resistance is a changeable one.

If instead of having the circuits of the secondary coils 23 and 211closed on themselves through the resistances 25 and 26, either or bothof such secondary coils Ais connected through its resistance to theexciting circuit, directly or through a transformer, as is indicated inFigs. 4, 5, and 6, the action is substantially the same. Because of theresistances 25 and 26 in such circuits, and the inductive character ofthe circuit including the coil l1, the fluxes which are produced by thecurrents in the secondary coils 23 and 24 are approximately inquadrature with the main flux produced by the main winding 11 eventhough such secondary coils 23 and 24 are connected to the excitingcircuit, so that the interaction vof the fluxes and eddy currents issubstantially the same, qualitatively if not quantitatively, whethersuch secondary coils are excited condire-tively from the excitingcircuit or are excited wholly by induction.

As shown in Fig. 7, the fingers 12 and 13, and 14 and 15, on one of eachpair of which a secondary coil is provided, may be on the member 17which completes the magnetic cir-cuit, instead of on the member 10 whichbears the main exciting winding.

T he resistance meter may be used to give a direct indication and adirect record of the value of any resistance 26 vwhich may be ductance,the action of themeter is substantially unaffected by variations in thevoltage, frequency, or wave-form of the excitinv circuit, for any suchvariations similarly a ect the twoinduction-meter elements.

It is not necessary that theedge 30 of the plate 16 :be a smooth curveas shown, or even that it be eccentric. My invention is not limited toany particular shape of such edge 30 but contem lates any posltion,shape, or construction o the plate 16 so that as such plate is moved avariation is produced in the conductance of the eddy-current paths insuch plate. This variation is preferably provided for at both pairs offingers, to produce an increase in the eddy currents at one pair offingers and a simultaneous decrease in those -at the other pair offingers; but it is obvious that this double action is not necessary, andthat equilibrium between the opposing forces may be obtained if the eddycurrents at only one setof fingers are varied. It is not essential thatthe two pairs of fingers, constitutin separate inductionmeter elements,shall e excited by a common exciting winding, or shall act on the sameeddy-current plate, or shall have their magnetic circuits completedthrough the same magnetic-material member 17, though I now prefer toprovide these things in common, as that seems to be the simplest andmost convenient arrangement; nor is it material whether the lingers andthe secondary coils therefor be on the same member l() which carries themain exciting winding 11 or on the member 17, as the fingers may beprovided at any convenient part of the magnetic circuit energized by thecoil 11 if in proper relation to the eddy-current plate or plates.

I claim as my invention:

1. An alternatlng-current resistance meter,

comprising two induction-meter elements, and a movable member includingone or more eddy-current plates which cooperate with said twoinduction-meter elements, said two induction-meter elements respectivelytending to move said movable element in op posite directions, and one ofsaid meterv elements being provided with a winding with which theresistance to be measured may be connected in circuit, said eddy-currentplate or 4plates being arran ed to have the conductance of the possib epath for eddy currents therein varied as said movable element is moved.

2. An alternating-currentresistance meter,

in such fingers, a secondary coil on one finger 1 of each pair, aresistance connected in circuit with one of said secondary coils, theother secondary coil being arranged to have connected in circuittherewith the resistance of which the value is to be measured, and amovable member having eddy-current-carrying means cooperating with bothpairs of fingers so that the reactions produced by the two pairs offingers tend to move said movable member in opposite directionsrespectively, said eddycurrent-carrying means associated with at leastone of said pairs of fingers being arrangedyffto decrease theconductance o the eddy-current path when the effect of. that pair offingers predominates and vice versa.

3. An alternating-current resistance meter, comprising two pairs offingers, main exciting means for producing alternating fluxes in suchfingers, a secondary coil on one finger of each'pair, a resistanceconnected in circuit with? one of said secondary coils, the othersecondary coil being arranged to have conneoted in circuit therewith theresistance of which the value is to be measured, and a movable memberhaving eddy-current-carrying means cooperating with both pairs offingers so that the reactions produced by the two pairs of lingers tendto move said movable member in opposite directions respectively, saideddy-current-carrying means being arranged to vary the relativeconductances of the eddy-current paths at the two sets -of fingers assaid movable member is moved.

4. An alternating-current resistance meter, comprising a core having twopairs of fingers, a main exciting winding for said core, a secondarycoil on one finger ofv each palr, a resistance permanently 1n circuitwith one of said secondary coils, the other secondary coil beingarranged to have connected in circuit with it the resistance of whichthe value is to be measured, and a movably mounted edd current plate injuxtaposition to both said pairs of fingers, the two pairs of fingersbeing arranged so their respective reactions on such plate tend to moveit in opposite directions, and the edge of such eddy-current plate beingarranged to approach or recede from at least one of said pairs oflingers as the eddy-current plate is moved and thus to vary theconductance of the path for the ,eddy currentsin such plate at suchfingers.

5. An alternating-current resistance meter, comprising two pairs of finers, main exc-iting means `for producing a ternating fiuxes in suchfingers, a secondary coil on one fin rer of each pair, one of saidsecondary coils eing arranged to have connected in circ-uit therewiththe resistance of whichthe value is to be measured, and a movable memberhaving eddy-current-carrying means coo erating with both pairs offingers so that t e reactions produced by the two pairs of fingerstend'to move said movable member in opposite directions respectively,said eddy-current-carrying means associated with at least one of saidpairs of fingers Abeing'. arranged to decrease the conductance of theeddy-current path when the effect of that pair of fingers predominatesand vice versa.

6. An alternating-current resistance meter, comprising two pairs offingers, main exciting means or producing alternating fluxes in suchfingers, a secondary coil on one finger of each pair, one of saidsecondary coils being arranged to have connected in circuit therewiththe resistance of which the value is to be measured, and a movablemember having eddy-current-carrying means cooperating with both pairs offingers so that the reactions produced by the two pairs of fingers tendto move said movable member in opposite directions respectively, saideddycurrent-carrying means being arranged to varyy the relativeconductances of the eddycurrent paths at the two sets of fingers as saidmovable member is moved.

7. An alternating-current resistance meter, comprising a core having twopairs of fingers, a main exciting winding for said core, a secondarycoil on one finger of each pair, one of said secondary coils beingarranged to have connected in circuit with it the resistance of whichthe value is to be measured, and a movably mounted eddy-current plate injuxtaposition to both said pairs of fingers, the two pairs of fingersbeing arranged so their respective reactions on such plate tend to moveit in opposite directions, and the edge of such eddy-current plate beingarranged to approach or recede from at `least one of said pairs offingers as the edd c urrent plate is moved and thus to vary t econductance of the path for the eddy c-urrents in such plate at suchfingers.

8. An alternating-current resistance meter, comprising aninduction-meter element provided with a winding with which theresistance to be measured may be connectedk in circuit, an eddy-currentplate cooperating with said induction-iifter element and movably mountedso that as it is moved by the interaction thereon of saidinduction-meter element the possible path for eddy currents therein isvaried in conductance, and velectromagnetic means o-pposing theemovementof said movable member under the action of said induction-meter element.

9. An alternating-current resistance meter, comprising a pair offingers, main exciting means for producing alternating fluxes in suchfingers, a secondary coil. on one of said fingers, said secondary coilbeing arranged to have connected in circuit therewith the resistance ofwhich the value is to be measured, a movable member having an edd-current plate cooperating with said two ngers so that the reactionproduced tends to move said movable member in one direction,electromagnetic means opposing such movement of said movable member,said eddy-current plate being arran ed to decrease the conductance ofthe e dy-'current path in such current plate bein arranged to a plate assuch plate is moved by the interaction thereon of the fluxes from saidlingers.

10. An alternating-current resistance meter, comprising acore having apair of fingers, a main exciting winding for said core, a secondary coilon one of said fin ers, said secondary coil being` arranged to aveconnected in circuitl with it Athe resistance of which the value is tobe measured, a movably mounted eddy-current plate in juxtaposition tosaidl fingers so that the reaction of said fingers on said plate ltendsto move the plate in a given direction, electromagnetic means op osinsuch movement of said movable mem r, t e edge of said eddyproach orrecede from such ngers as the e dy-current plate is moved and thus tovary the conductance of' the path forthe eddy currents in such plate atsuchv fingers;

11. An alternating-current resistance meter, comprising two pairs of finers, main excitin means for producing la ternating fluxes in suchlingers, a secondary coil on one finger of each pair, one of saidsecondary coils being arran d to have connected in circuit therewith t eresistance of which the value is to be measured, and a movable memberhaving v.eddy-current-carrying means cooperating with both pairs offingers so that the reactions produced by the two pairs of fingers tendto move said movable member in opposite directions respectively, saidedd -current-carrying means associated with at east one of said pairs oftingerslbeing arrangedl to decrease the conductance of the eddy-currentpath when the eiect of that pair oftingers predominates and vice versa,and the circuits of said two secondary coils being of the same nature;

12. An alternating-current resistance meter, comprising two pairs of finers, main exciting means for .producing a ternating fluxes in suchfingers, finger of each pair, one of said secondary coi s being arran tohave connected in circuit therewitht e resistance of which the value isto be measured, and a movable meinber having eddy-current-carrying meanscoo erating with both pairs of fingers 'so that t e reactions producedby the two pairs of fingers tend to move said movable member in oppositedirections respectively, said eddy-current-carryin means being arrangedto vvary the relative conductances of the eddy-current aths at the twosets of fingers asl said mova le member is moved,l and the circuits ofsaid two secondary coils being of the same nature.

13. An alternating-current resistance meter, comprising a core havin twoairs of fingers, a main exciting wincing or said core, a secondary coiloirone inger of each pair, one of said secondary coils being ar-`measured, and a movably current plate in juxtaposition to both saida-secondai'y coil on one ranged to have connected in circuit with it theresistance of which the value is to be mounted eddypairs of fin ers, thetwo pairs of fingers being arrangev so their respective reactions onsuch plate tend to move it -in o posite directions, and the ed e of suche dy-ciirrent,

plate being arrange to approach or recede from at least one of saidpairs of fingers as the eddy-current plateis moved and thus to vary theconductance eddy currents in such plate at such fingers, and thecircuits of said two secondary coils being of the same nature.

14. An alternating-current resistance meof the path for the ter,comprising two induction-meter elements, and a movable member includingone or more. eddy-current 'plates which cooperate wth said twoinduction-meter elements, said -two induction-meter elementsrespectively tending to move said movable element in oppositedirections, each of said two induction-meter elements being providedwith a winding, and said respective winding for the two induction-meterelements ing similar in nature, and one oi said windings being arrangedto have the resistance to be measured connected in circuit withit, andsaid edd -current plate or plates being arranged to ave the conductanceof the possible path for eddy currents therein varied as said movableelement is moved.

15. An alternating-current resistance meter, comprising twoinduction-meter elements, and a movable member including one or .moreeddy-current plates which coo -f erate with said two induction-meter eements, said two induction-meter elements respectively tending to movesaid movable element in opposite directions, each of said twoinduction-meter elements being provided with a` winding, and saidrespective windings for the two induction-meter elements being similarin nature and so connected to an alternating-current circuit that they.are similarly variable in effect upon change in voltage of suchalternating-current circuit.

16. An alternating-current resistance meter, comprising a pair offingers, main exciting means for producing alternating fluxes in suchfingers, a secondary coil on one of said lingers, said secondary coilbeing arran ed to have connected'in circuit therewith t e resistance ofwhich the value is to be measured, a movable member having aneddy-current plate cooperating with. said two lingers so that'thereaction produced tends to move said movable member in one direction,means opposing such movement of said movable member, said eddy-currentpxllate be' arran d to' decrease the conctance o the e ly-current pathiii such plate as such plate is moved by the interaction thereon of thefluxes from said fingers.

17. An alternating-current resistance meter, comprising a core having apair. of fingers, a main exciting winding for said core, a secondarycoil on one of said fingers, said secondary coil being arranged to haveconnected in circuit with it the resistance of which the value is to bemeasured, a movably mounted eddy-current plate in juxtaposition to saidfingers so that the reaction of4 said ingerson said plate tends to movethe plate in a given direction, means opposing'such movement of saidmovable member, the edge of said eddy-current plate being arrangedtoapproach or recede from such fingers as the eddy-current plate ismoved and thus to vary the conductance of the path for the eddy currentsin such plate at such fin ers.

18. An a ternating-current resistance meter, comprising twoinduction-meter elements, and a movable member including one or moreeddy-current plates which co-operate with and are transverse to the fluxof said two induction-meter elements, said two induction-meter elementsrespectively tending to move said movable element in oppositedirections, and one of said inductionmeter elements being provided witha winding with which the resistance to be measured may be connected incircuit, said eddycurrent plate 0r plates being arranged to have theconductance of the possible path for eddy currents therein varied assaid movable element is moved.

19. An alternating-current resistance meter, comprising aninduction-meter element provided with a windin with which the resistanceto be measure may be connected in circuit, an eddy-current platetransverse to the flux of and co-operating with said induction-meterelement and movably mounted so that as it is moved by the action thereonof said induction-meter element the possible path or eddy currentstherein is varied in conductance, and electromagnetic means opposing themovement of said movable member under the action of said inductionmeterelement.

20. An alternating-current resistance meter, comprising twoinduction-meter elements, and a movable member including one or moreeddy-current plates which co-Operate with and are transverse to the fluxof said two induction-meter elements, said two induction-meter elementsrespectively tending to move said movable element in opposite direction,each of said two inductionmeter elements being provided with a winding,said respective windings for the two induction-meter elements beingsimilar in nature and one of said windin s being arranged to have theresistance to e measured connected in circuit with it, and saideddycurrent plate or plates being arranged to have the conductance ofthe possible path for eddy currents therein varied as said movableelement is moved.

In witness whereof, I have hereunto set my hand at Indianapolis,Indiana, this 11th day of May, A. D. one thousand nine hundred andtwenty one.

DONALD J. ANGUS.

